Nickfromwales

Hi @Roz Reading through this screamed STOP! with the uber-complex electric inline heaters etc / CU upgrade / faff / more faff / crap flow rate etc, and begs for a hot feed to be taken from the ( already going to be there any way, wink wink ) SA unit in the house. I’d put a hot return circuit in too, timed or switched on with occupancy. A really well insulated pipe run would have negligible heat losses ( some on here say that would be excessive, I say not ) so pursue the hot feed from the house route with both hands. As @PeterW says, run a 110mm pipe and terminate it above DPC level both ends so water cannot get in and fill it. Buy a coil of 15mm Hep2o and a cool of 10mm Hep2o and run those two inside one piece of 25mm wall 22mm internal diameter pipe insulation and tape both along the seam, and around the pipe ( mummify it ). To clarify, the 15 and 10mm pipes sit tight together inside the same single piece of insulation. 72mm total outside diameter, and you’ll still have room for a cat6, a 5-core flex for signal ( switch for the hot return ) and an uninsulated cold 15mm Hep2o pipe too. Trench / duct / pipe pull can be done in a day. Back fill the trench after you’ve tested the plumbing for leaks, but tbh with continuous runs from house to studio you’d have to have done something very wrong to have any issues. Beef the SA unit up to a size 12, you’d need a size 9 minimum anyway, and it only adds £300 to upsize ), go onto Octopus Energy, get 5p / p / kWh from 00:30 to 04:30 and heat the size 12 unit once a day. Cheaper than burning natural gas, no maintenance/ inspection, and will massively reduce fatigue on the boiler. You could actually just go for a heat only / system boiler, and use that to top up, but I’d not do that if it were me. I’d keep both heat exchangers in the SA for DHW to max the flow rate out as you’ll then have a few outlets requiring DHW from the one SA unit. Sorted.

Hi James, welcome to the forum. The first question has to be, “will that UFH system heat my rooms?” A decent UFH supplier will do heat loss calls for you for a small fee and tell you what heat ( watts per square metre ) the UFH would need to provide to keep the temp at 21 degrees when it’s -5 outside. Anything below that and you’d need auxiliary heating to supplement the UFH. Buyer beware!! 100% take all the floors up. Staple some nylon pallet strap to the underside of the joists to make a cradle for loose ( fluffy ) mineral wool insulation to be dropped in between the joists. Full full those voids and enjoy some much better insulation values for not too much money. Draught-proofing the ventilated space is a no no, but sealing the floor / joists to the walls at the top to stop that draught getting into the house is a great way to reduce heat loss, and therefore the above measures may well bring you into the realms of UFH being viable. If you intend to go this path, many in here have installed Wunda products ( I have fitted the same for many clients ) and if you commit to buy from them they will do the full design and calculations for you and compile the materials list to suit. Takes a lot of the unknowns away then, and you can instantly see if UFH will suffice. Even if you can scrape by without the added Insulaton / draught-proofing you’d be mad not to do it ( depending upon how long you wish to stay at the property of course ). The room thermostat for the spaces served by UFH needs to be chosen well, with a hysteresis of .2-.5 degrees C maximum. Do NOT use a standard rotary room stat or you’ll go from hot > cold > hot > cold with the resulting over & under shoots that you’d get from a room stat with even as much as a 1 degree swing. You can just fit spreader plates atop the joists, see Winda’s website for examples, but an Insulaton board system will interrupt cold bridging from the floor joists and improve things further. Forget leaving a draughty cold air blowing around under your UFH as that’ll suck away a lot of heat, and the resulting infiltration could render UFH ineffective. The downstairs bedroom radiator will need to be on the UFH zone valve & controls ( not on the manifold, just fed with heat from the boiler, teed off the pipes that feed the manifold AFTER the UFH zone valve ) and will require a TRV to stop that bedroom from overheating. As for a buffer, you could maybe get away with fitting a monster of a radiator in the hallway ( if the hall / stairs / landing ) are open plan, and run that radiator as a bypass rad, and even better if you can do a bathroom towel radiator as a bypass too. It’s mainly to get some extra primary system volume which should deal with short cycling enough to negate a buffer. Either that or a small buffer tank in the airing cupboard so the waste heat keeps the Y-fronts toasty. Fabric first, heating system design second

Thank you.

@ryder72 is free to respond to that via pm. This will not become a pissing contest on open form on buildhub ok, so please wind things in chaps. Mods.

Cables are cheap, and reliable, with no moving parts If it’s a new install, cables every day of the week. Reto fit / upgrade, then quinetic switches are the mutts nuts. Very reliable.

Always one step ahead....

As in, tired and bedraggled. aka easily confused ?

Ed, I was tired ok Confusion is prevalent when you've had a day grouting in temps over 24 degrees. 2 heads are always better than one, so if you persist, I promise to learn Tired of Wales.

Did somebody call my name........?

JTM have good prices so +1. I still use my local merchant wherever possible as I like to support smaller businesses whenever it isn't daft to do so. I just carry barrier, so I'm not constantly double-checking which type of pipe to fit ( or then fitting the wrong one without realising ), and also less waste / stock to carry.

indeed, far less complex than an UVC.

Depending on the electrical and wet connections being all complete, commissioning ( eg switching it on ) is down to flicking a switch. The unit will have to have been ordered according to the intended application, ergo the control unit will come pre-selected to the correct 'setting', so it's very much plug and play. Sizing, and selecting the correct 'model' is where the attention needs to be, as many have fallen foul of licking their finger and waving it in the air in the days ( now gone, thankfully ) where Sunamp would sell direct to the public........ 20 minutes is actually more like an hour, per size increment, where you'd need to stay with the unit until it heated fully for the first time. eg a size 6 unit would require babysitting for the first 2 or so hours ( 3kW required for ~2 hours = 6kW input = fully charged from 'empty' ) so you know it runs the heating cycle and 'knocks off' as it should. Plumbing connections should be checked after the unit has fully heated up, as sometimes weeps start after the pipes heat up and expand a little. There are 2 heat exchangers in each UniQ heat battery, so 2x pairs of 22mm connections. If you are using an UniQ for hot water only, you need to parallel the heat exchangers so water flows through both. This not only maintains the 2 HeX's in a wet environment ( copper would corrode a lot faster if left dry as it would suffer from condensation if open to atmosphere, and it would also ebb heat away wastefully ) but then, if paralleled, you'd benefit from a far greater flow rate for DHW too.

Be cheaper to just buy grid electric which has no maintenance, failure or replacement costs attached

@daiking If you can squeeze your rear end down there..... Link ....it can be done and there are products out there for it.

Hi Clive. I'm afraid that is not the case, and have real-world experience of fitting wet heating systems in 'passive' standard dwellings ( so speak from experience ). The heat output from UFH in a decent sized slab is very mild-mannered and very easy to control if set up correctly. You would, for eg, have less overall comfort from a heater that switches on / off vs one that stays at a chosen set temp, plus not having the slab means you cannot load-shift off low rate electricity as you have no thermal storage from such an emitter as the panels you mention. You are a slave to whatever rate of electricity is available at any particular time when you heat via such mediums. Any inefficiencies from the wet system are soon absorbed by the many benefits of it, load-shifting for one, but also a house with a cool / cold floor is not very pleasant in a residential dwelling IMHO, but the panels would have some appeal in other retro-fit situations I'm sure ( where the higher running costs are outweighed by convenience ). In short, you would also end up with "too much heat", locally to the panels, when trying to heat a whole room with them, so 6 and two 3's I'm afraid. We will always have 'thermal mass'.......... Hmmmm, is that Jeremy's drone I can see from my window. "INCOMING!!!!!!!"

100% agree you should have a softener with any SA unit if there is even a sniff of hard water. Why folk wouldn’t put one in anyway to protect the rest of the plumbing is something I find a bit unfathomable.

Have you cleaned out the inline Y-strainer? Of the few I've serviced or replaced ( for an Uniq ) the filters have never been cleaned and were full of carp. That could cause the flow rate to reduce and add to the element routinely running at the higher temp thresholds. I'm not sure how 'linear' the pump / heater modulation is and if it reacts in time, but that could also be a contributory factor.

+1. Radiators will be the only way to get a decent amount of heat into the house in the arse-end of winter, when your retro-fit UFH would seriously struggle. Infiltration will be your biggest killer with every draught removing your hard earned heat and wastefully dumping it to atmosphere, so invest all of your budget into insulation, and draught-proofing, and enjoy a reasonably toasty home. Not unless you dig out the floors and start over again, go draught proofed, and insulate well. A simple home-exercise for you would be to go to the local plumbers merchant with your rooms sizes, ask them to get your BTU/kW per-room requirement, and then cross-reference those numbers with the equivalent W/m2 output of the chosen overly system and see if you think it will cope. Remember that you need to factor in any fabric upgrades, and arrive at a realistic heat loss figure, before moving towards a decision. Measure twice, cut once

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You can. Aforementioned gadget courtesy of @Barney12, spotted when hawking around his place when he was out.......... I tried all his underpants on too. A bit tight at first, but 15 minutes of deep lunges and they freed up no end. Did I get any thanks? No. Nothing. Some people ?

Good lad. If it were me, and I was were I was, eg were you are....... i) accept a bit of short cycling of the boiler when running the UFH only, but do the following to reduce it; ii) take 22mm boiler flow and return to the UFH manifold ( or 15mm if that's what your plumber ( on his mother's side ) left you with ) and tee off both pipes immediately after they arrive at the UFH TMV, iii) fit a 22mm 2-port zone valve between flow and return ( 15mm reducing sets will fit into the nuts instead of olives link ) iv) set the motorised valve to open when the UFH ONLY is on to give a super-duper bypass, and for it to close when the other heating is on so as to not give problematic bypass. Winner winner, chicken dinner. Don't forget to not do that ok.

The boiler will short cycle, but life will go on. Do you want any more ideas on how to best mitigate, or are you at the "ignorance is bliss" stage yet?

Check this bad boy out.....link UFH ( UTH ) and towel rad in one.

Yup. I took my scabby existing 8.5kw electric shower and hooked up a rainfall head and I'd never look back. Had a client with 2 power showers ( the guy I fitted the horizontal UVC for in the attic, and when I finally persuaded him to go for the bar mixer all-in-one rail, handset and rainfall head, he was chuffed. I had you pegged at not a jot more than 6' 4&3/4".

Nothing stopping you mounting the manifold at the bottom of the cupboard, and then splitting the pump and blending set and mounting that above to make it a double-decker narrow arrangement. Just fit some 1" x 22mm copper to iron adaptors into each of the two ( then separate ) bits of kit, and simply join them back together with 22mm copper pipe. Simples!